1. Field of the Invention
The present invention relates to an image processing method in which memory means to store image data is used, and more particularly to an image processing method applicable to apparatus, such as facsimile devices, which electrically transmit image data.
1. Description of the Prior Art
An electrical image transmission system in a facsimile device with a high-density image reader has a structure such as shown in FIG. 1.
That is, in FIG. 1, reference numeral 1 denotes a high-density image reader which reads an image on an original document. The run-length of the read image is determined by a run-length counter 2. An MR (modified read) encoder 3 converts the determined run-length into a corresponding MR code which is then stored in an image memory 4.
A high-density and image contains many image data which require a memory of large capacity to be stored in.
In view of this, before delivering data to a transmitter 5, the transmission system compresses image data using a compression system for use in electrical transmission applications and stores the compressed data in a memory of a relatively small capacity.
As this image compression system, a two-dimensional compression code system which includes a MR (modified read) system, a modified MR (MMR) system or the like has been employed in accordance with CCITT's recommendation.
When image data are compressed and stored in a memory by means of such a system, however, it is impossible to directly change the density of pixels from image codes themselves in a line because the MR or MMR system is a two-dimensional compression system which compresses data on the basis of the data in the preceding line.
It is therefore extremely difficult to change the density of image data compressed and stored in the memory by the above-mentioned compression system directly before or during communication.
This causes a problem when the image data stored in the memory are transmitted to a plurality of called parties (receivers). For example, if the stored image data are for a B4 size and a receiver can only record a B5 sized image, transmission of the data for the B4 sized image to this receiver is impossible. In other words, no transmission has been possible to any receivers other than a receiver which can record a B4 sized image.